Agastache 'Black Adder' (Agastache hybrid): Dark Purple Pollinator Magnet

Overview

Agastache 'Black Adder' (also spelled 'Blackadder') is a hybrid hyssop bred by Dutch horticulturist Janssen. It combines the best traits of its parents: dark purple flower spikes, aromatic anise-scented foliage, and a long bloom season from midsummer to frost. A pollinator powerhouse.

Botanical Description

Upright, clump-forming perennial 60–90 cm tall. Stems square, dark. Leaves are ovate, toothed, gray-green, strongly anise-scented. Flowers are tubular, deep violet-purple, densely packed in spikes 10–15 cm long, blooming July–October. Sterile hybrid—does not self-seed.

Taxonomy

Family:	Lamiaceae (lay-mee-AY-see-ee)
Genus:	Agastache (ah-gas-TAH-kee)
Cultivar:	'Black Adder' (aka 'Blackadder')
Hybridizer:	Janssen

Growing Conditions

• Light: Full sun.
• Soil: Well-drained, average to lean; essential for winter survival.
• Water: Low to moderate; drought-tolerant once established.
• Hardiness: USDA zones 5–9; better winter survival in dry soils.

Garden Uses

Perennial borders, pollinator gardens, herb gardens, meadow plantings. Combines beautifully with golden rudbeckia, purple coneflower, Russian sage, and ornamental grasses. The dark flowers create depth in the border.

Notes

Deadhead to prolong bloom. Cut back in late winter. Excellent cut flower. RHS Award of Garden Merit. One of the most reliable, long-blooming Agastache cultivars for temperate gardens.